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New genetic testing guidelines induce debate

Issue: June 2012

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The recommendations caution against routine testing in the absence of proven treatment, while proponents say supportive clinical studies already exist.

The American Academy of Ophthalmology developed a set of guidelines for genetic testing in individuals with inherited eye disease, noting the possible risks associated with such testing. However, some clinicians fear the recommendations may be misinterpreted.

The American Academy of Ophthalmology’s (AAO’s) guidelines, in summary, recommend: offering genetic testing when clinical findings suggest a Mendelian disorder whose causative genes have been identified; using laboratories approved by the Clinical Laboratories Improvement Amendments; providing the test results to patients; avoiding direct-to-consumer genetic testing; avoiding parallel testing; and avoiding testing in most asymptomatic minors with untreatable disorders.

One additional recommendation with which some have taken issue says clinicians should “avoid routine genetic testing for genetically complex disorders such as age-related macular degeneration and late-onset primary open angle glaucoma until specific treatment or surveillance strategies have been shown in one or more published clinical trials to be of benefit to individuals with specific disease-associated genotypes.”

Rationale behind release of guidelines

Mathew W. MacCumber

“Over the last few years, there has been a proliferation of genetic tests for ophthalmology, for multigenic disorders such as macular degeneration, and there have been efforts by genetic testing companies to market their products to consumers over the Internet,” Mathew W. MacCumber, MD, PhD, one of the authors of the AAO guidelines, said in an interview with Primary Care Optometry News.

“It was felt that there should be some policy statement made to discourage direct-to-consumer marketing because the interpretation of these test results can be complex, and there could be important decisions made based on them,” he said. “The interpretation of the results should be conducted by a physician, or a genetic counselor, at least.

“Now, that’s not to say that in the future we won’t be able to direct care based on genetic tests,” Dr. MacCumber continued. “I think there are certain situations where genetic tests are very useful.”

Misinterpretation of guidelines?

Jeffry D. Gerson

Some doctors may misinterpret the guidelines, according to Jeffry D. Gerson, OD, of WestGlen Eyecare in Shawnee, Kan., told PCON.

The recommendation regarding waiting for “specific treatment or surveillance strategies” does not seem to be based on currently available scientific information, he said.

“It is important to recognize the power of genetic testing,” Dr. Gerson said. “The fact that the AAO has set such guidelines shows that the group recognizes potential value in it. I agree that any genetic testing should be used only when scientifically sound and appropriate, and with the needed follow-up to explain the results to the patient.”

Clinical studies support early intervention

However, in the case of dry age-related macular degeneration (AMD), sufficient published, scientific evidence shows how genetic testing can help stratify risk of conversion from dry to wet AMD, he said. Therefore, genetic testing can help clinicians better understand each patient’s condition and allow for individualized counseling and care, Dr. Gerson said.

According to Brent Zanke, MD, PhD, FRCPC, chief medical officer at ArcticDx, developer of the genetic test, Macula Risk, “The ability of AMD genetic testing to identify persons at high risk for progression has been consistently reported by well-respected investigators publishing in high impact clinical journals. The use of genetics to predict progression risk has been established.”

David W. Nelson

“In the case of macular degeneration, there already exists sound information supporting the use of genetic tests to enable early intervention,” private practitioner and ArcticDx vice president for optometry professional relations, David W. Nelson, OD, MBA, told PCON. “ArcticDx agrees with the AAO guidelines for the most part, but in the area of AMD, it’s well documented that these tests have a high predictive power.

“You can really make a difference when you preventively counsel an AMD patient,” Dr. Nelson added.

“We’re not restricting it,” Dr. MacCumber clarified. “We’re just making recommendations as a policy statement. Regarding the multifactorial conditions, such as AMD, it was felt that there isn’t, at this time, an intervention, or even an improved surveillance strategy, where genetic testing has been proven by a clinical trial to improve management.

Michael J. Tolentino

“Until we have an intervention that has been proven effective, we do not feel that genetic testing should be used routinely in these more complex disorders,” he said.

“Currently available genetic tests for AMD have attributable risks greater than 0.80, which is a highly predictive test for development and progression of the disease,” Michael J. Tolentino, MD, a member of the PCON Editorial Board, said in an interview. “These tests can be used to stratify patients who need closer monitoring and more emphatic counseling on modifiable risk factors.”

Closer monitoring, leading to earlier detection, could potentially reduce the number of intraocular injections and improve final visual results for the exudative AMD patient, Dr. Tolentino added.

“The highly predictive, clinically beneficial tests for AMD should not be clumped together with other genetic tests,” he said. – by Daniel R. Morgan